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The impact of job characteristics on the health benefits of healthy lighting systems in workplaces
Presented by: Anagha Ajaykumar
Supervisor: Dr. Wendy Davis
Visual and non –visual impacts of
light
Adverse effects of
artificial lightLab studies
Current healthy Lighting Systems
Field tests
Possible factors of impact
Factors in focus
Aim & Hypotheses
Research methodology
Discussion & Conclusion
Visual & non visual impacts of light
Visual function:
• Image forming
• From rods and cones in the retina to the
visual cortex in the brain
• Depends mostly on amount of light entering
the eye.
Neural pathways (van Bommel & van den Beld, 2004).
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Non - visual function:
• Mediates photo biological functions
• From the Intrinsically Photosensitive Retinal
Ganglion Cells (ipRGCs) to the Super
Chiasmatic Nuclei (SCN)
• Depends on
• Time of exposure
• Illuminance
• CCTNeural pathways (van Bommel & van den Beld, 2004).
Visual & non visual impacts of light
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Photo biological impacts
• Stabilizing Core Body Temperature (CBT)
• Alertness
• Circadian rhythm
• Heart rate
• Hormonal production
• Melatonin (sleep hormone)
• Cortisol (stress hormone)
(van Bommel & van den Beld, 2004)
Natural rhythm of hormonal production under 24 hr natural light cycle (van Bommel,
2006).
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Adverse effects of artificial light
• Static illuminance and CCT levels
• Overexposure
• Disrupts melatonin secretion
• Causes circadian phase shift
• Sleep impairment
• Disrupts Cortisol secretion
• Increases tiredness
• Start of fatigue
(Aries, 2005)
24 hr cortisol cycle . Image from: https://www.integrativepro.com/Resources/Integr
ative-Blog/2014/The-Role-of-Cortisol.aspx
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Fatigue in the workplace
Excessivework
demands
Exhaustion of personal resources
Fatigue Absenteeism
Static artificial lighting
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Lab studies
• Studies show indirect co relation between bright light (5000 lx) and fatigue levels.
• This effect is independent of the time of day of exposure (Ruger et al., 2005)
• Also Independent of eye correction, chronotype (sleep habits) and other individual characteristics (Aries M., 2005).
• Lower fatigue levels are observed under dynamic lighting (500 – 1800 lx), varying in 30 min intervals, compared to static lighting (500 lx for 8 hrs) (Hoffmann et al., 2008).
Course of subjective fatigue levels through day (left) and night (right) time exposure of
bright & dim light. (Ruger et al., 2005)
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studies
Current healthy Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Current Healthy Lighting Systems
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studies
Current healthy Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Image from http://humancentriclighting.com/wp-content/uploads/2012/07/Stan-Article-SSL1.pdf
• Develop healthy lighting systems for:
• Schools
• Workplaces
• Health centers
• Domestic environments
• Claims to improve user:
• Health and well being,
• Task performance
• Need for recovery
• Need for recovery: is that feeling of exigency to take a breather from current demands. It marks the beginning of fatigue and therefore has a direct correlation with it (Sonnentag & Zijlstra, 2006).
("Lighting For People – web-based platform for high quality information on solid state lighting in Europe", 2016) & (Humancentriclighting.org, 2014)
Top & middle: Lightingforpeople logo. Image from: http://lightingforpeople.eu/.
Bottom: Human centric lighting society logo. Image from:
http://humancentriclighting.com/wp-content/uploads/2012/07/Stan-Article-
SSL1.pdf
Current Healthy Lighting Systems
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studies
Current healthy Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Field studies
• Dynamic lighting patterns have been
employed in workspaces and their
effects observed.
• Measurements where made on the
claimed health benefits:
• Need for recovery
• Alertness & vitality
• Sleep quality
• None of the claimed benefits where
observed, that was significant
enough to be considered.
(de Kort & Smolders, 2010) Dynamic lighting pattern employed by de Kort & Smolders, 2010.
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field tests
Possible factors of impact
Factors in focusAim &
HypothesesResearch
methodologyDiscussion & conclusion
Within person Sleep quality
Health
Fatigue
Job characteristics
Job demands
Job control
Off – job activities
Amount of time spent in job related activities
Amount of time spent in household and child care activities
Amount of time spent in leisure activities
Experience quality
Possible factors of impact
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field tests
Possible factors of impact
Factors in focusAim &
HypothesesResearch
methodologyDiscussion & conclusion
Factors in focus
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impact
Factors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Job demands
Drastic working situations
OvertimeWork under
pressure
Time constraints
Job demands:
• Direct correlation has been observed
between job demands and need for
recovery levels (Sonnentag et al.,
2006).
Job control:
• Is the autonomy of the individual on
his/her task for:
• Taking breaks,
• Composing one’s own method of working and
• Ability to rearrange schedules to suit their convenience.
• A negative correlation has been
observed between job control and need
for recovery.
(Jackson, Wall, Martin, & Davids, 1993).
Job control
Job demand
Need for recovery
Fatigue
+
-
+
Factors in focus
Healthy Lighting Systems
-
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impact
Factors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Aim of the proposal
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Aim: A field study is proposed here that would aim to compare the need for recovery
levels of a varied group of employees with different combinations of job demand and
control levels under dynamic versus static lighting conditions.
Hypotheses
Job control
Job demand
+ =
Job control
Job demand
+ =
Job control
Job demand
+ =N N
Health benefits of HLS
Health benefits of HLS
Health benefits of HLS
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Research methodology
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
1. Study group:
a) A large group of subjects (n ≥ 100).
b) In varying job positions and responsibilities.
c) Job demand and control levels to be measured for each individual, prior to beginning study.
d) Employees to be grouped according to job demand and control levels.
Me
Job demand
Job control
Job demand
Job control
Job demand
Job control
Job demand
Job control
Job demand
Job control
N
Job demand
Job control
N
Job demand
Job control
NN
1.1 Measuring job demands:
a) Via self – administered questionnaire
b) Questions adopted form Job Content Questionnaire (JCQ) (Karasek et al., 1998)
1.2 Measuring job control:
a) Via self – administered questionnaire
b) Questions from Dr. Greenbergers’ report on “Personal control at work” (1981).
A. My job requires me to work fast:
Strongly disagree
Somewhat disagree
Neutral
Somewhat agree
Strongly disagree
A. I have control over my schedule:
Strongly disagree
Somewhat disagree
Neutral
Somewhat agree
Strongly disagree
Research methodology
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
2. Study period:
a) To be conducted in darker winter months (July – August)
3. Study methodology:
a) Study group can be divided into 2.
i. Both groups should be in identical office spaces.
b) Each group can be exposed to the two lighting conditions alternatingly for a period of 2 weeks each.
i. Total 4 weeks
c) Subjects fill out the ‘need for recovery’ questionnaire at the end of the day, before bed – time.
WEEK 1 & 2
A B
WEEK 3 & 4
A B
Research methodology
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
4. Measuring need for recovery levels:
a) Questions adopted from ‘Need for recovery’ scale (van Veldhoven et al., 2003)
5. Lighting settings:
a) Same dynamic lighting pattern as employed by de Kort (2010)
b) Tunable LEDs controlled via central control module.
c) Same luminaires to be used under static conditions.
A. I found it hard to unwind tonight by bedtime:
Yes
No
Dynamic lighting pattern employed by de Kort & Smolders, 2010.
Research methodology
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
• Data analysis:
• Regression analysis to be done to
identify correlations between job
characteristics and need for recovery
levels.
• Possible results:
• For those who are already under great work pressure, lighting changes might go unnoticed and might render futile.
• Might be effective in enhancing the work experience of the relaxed employee.
I don’t care anymore
Research methodology
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
Employee number
Phase 1 Phase 2
Week 1
Week 2
Week 3
Week 4
Static
Employee 1
xx xx
Employee 2..
Dynamic
Employee 3
Employee 4…
Table to input data on need for recovery levels of different employees throughout the period of the
study and under different lighting conditions
Discussion & conclusion
Visual and non – visual impacts of light
Adverse effects of artificial light
Lab studiesCurrent healthy
Lighting Systems
Field testsPossible factors
of impactFactors in focus
Aim & Hypotheses
Research methodology
Discussion & conclusion
• Proposed methodology can also be used to
study impacts of lifestyle parameters.
• This experiment would just be an initial
contributor to many more studies to come,
in learning to optimize Healthy Lighting
Systems.
Off – job activities
Amount of time spent in job related activities
Amount of time spent in household and child care activities
Amount of time spent in leisure activities
Experience quality
Key references
• van Bommel, W., & van den Beld, G. (2004). Lighting
for work: a review of visual and biological
effects. Lighting Research And Technology,
36(4), 255-269.
• Aries, M. B. C. (2005). Human lighting demands:
healthy lighting in an office environment.
Technische Universiteit Eindhoven, Faculteit
Bouwkunde.
• Hoffmann, G., Gufler, V., Griesmacher, A., Bartenbach,
C., Canazei, M., Staggl, S., &
Schobersberger, W. (2008). Effects of
variable lighting intensities and colour
temperatures on sulphatoxymelatonin and
subjective mood in an experimental office
workplace. Applied Ergonomics, 39(6), 719-
728.
http://dx.doi.org/10.1016/j.apergo.2007.11
.005
• Ruger, M. (2005). Time-of-day-dependent effects of
bright light exposure on human
psychophysiology: comparison of daytime
and nighttime exposure. AJP: Regulatory,
Integrative And Comparative Physiology,
290(5), R1413-R1420.
http://dx.doi.org/10.1152/ajpregu.00121.
2005
• Humancentriclighting.org. (2016). Human Centric
Lighting. [online] Available at:
http://humancentriclighting.org/
[Accessed 25 May 2016].
• Lighting For People – web-based platform for high
quality information on solid state lighting
in Europe. (2016). Lightingforpeople.eu.
Retrieved 22 May 2016, from
http://lightingforpeople.eu/
THANK YOU